(A) Field of the Invention
The present invention relates to an electropolishing electrolyte and method for planarizing a metal layer using the same, and more particularly, to an electropolishing electrolyte including an alcohol additive and method for planarizing a metal layer using the same.
(B) Description of the Related Art
In semiconductor manufacturing technology, an ideal planar surface without altitudinal difference is necessary for high-density photolithography process to avoid exposure scattering so as to realize the precise pattern transfer of integrated circuits. Chemical-mechanical polishing technology is a widely used surface planarization technology in current semiconductor fabrication process. However, the chemical-mechanical polishing technology faces some important theories in actual applications, such as pattern effect, removing selection ratio, dishing, scratching, and insulating abrasion and cleaning after polishing. In addition, to meet the low stress requirement for 12″ wafer and low dielectric constant materials, the chemical-mechanical polishing technology will confront with more challenges.
Compared to the chemical-mechanical polishing technology, the electropolishing technology has become an alternative solution of the chemical-mechanical polishing technology because of several advantages such as reducing scratching, reducing particles absorption and reducing discard solution, high polishing rate and no pressure applying on the wafer. In the copper conductor process at the back end of the semiconductor fabrication, the electroplating technology is generally used to form a copper conductive layer. However, the copper conductive layer will produce a step height due to trenches on the surface of the wafer, which will further influence the planarization efficiency of a subsequent electropolishing process.